One well known press for retreading tires consists of a standard outer heat ring which holds a plurality of segmented matrices that contain the tire tread pattern. A special curing tube is inserted within the casing of the tire being retreaded and secured therein by a collapsible curing ring. This tire body containing the centering ring and special inflated curing tube is supported on a plywood board which supports one side of the tire sidewall area. A centering ring is then mounted on a central post in the center of the cure press and has a vertically extending outer annular wall which abuts against the lowermost peripheral edge of the tire bead area to maintain the tire centered within the press. The matrix covers approximately one-third of the tire section height (tread area and adjacent side wall areas), with the bead area being relatively unrestrained and free to move within the press during the curing operation. Such presses are generally referred to as having a free floating bead configuration since the bead area of the tire is freely movable within the press and is substantially unrestrained against movement during the curing of the retread strip on the outer periphery of the tire.
Although such cure presses have proved satisfactory for the retreading of tires, they possess certain undesirable characteristics. The curing tube is a specially designed inflatible member requiring a special construction for each general range of tire sizes and must be replaced after a relatively small number of retread operations. Also, the collapsible curing ring which maintains the inflatible tube in position within the press is relatively heavy and difficult to install and remove within a tire casing thereby increasing the amount of work and effort required by the operator performing the retread operation. In addition, the plywood boards on which the tire and centering rings are supported require frequent replacement. Likewise, the tire centering ring is relatively heavy and is difficult to handle increasing even further the effort required by an operator during the retreading of a tire since the centering ring must be installed and removed for each retread operation together with the special inflatible innertube and collapsible curing ring used therewith.
Many of the problems and disadvantages with cure presses having a free floating bead configuration and construction described above are believed to be overcome by my improved cure press described below. Although other cure presses are known in the prior art which trap the bead area of the tire during the retread operation, none are believed to accomplish the desired results in the same manner as the improved cure press of my invention.
U.S. Pat. No. 1,917,110 discloses a retreader in which the tire casing bead is trapped during curing by a curved annular rim having upturned end flanges similar to a usual vehicle tire rim. U.S. Pat. No. 2,597,550 uses a rubber strip bonded about a metal insert for sealing the bead area of the tire against a complementary shaped recess formed in an annular ring-like member which is trapped between a pair of movable mold sections. U.S. Pat. No. 3,118,181 uses an inflatible tube which presses the bead area of the tire against the edges of split mold sections which extend about the sidewalls and tread area of the tire. U.S. Pat. No. 3,925,129 shows another tire cure press which uses a standard annular shaped rim for trapping the bead area of the tire with the sidewall areas being restrained by the sidewalls of the matrix. U.S. Pat. No. 3,969,179 discloses another cure press which uses an annular rim which is retained within a lower mold section for trapping and holding the bead area of the tire while a cure bag is inflated within the tire. The sidewalls of the tire are held in position by a pair of mold sections.
Several foreign patents also disclose other prior art retreading presses which trap the bead area of the tire such as U.K. Pat. No. 1,026,536 which uses a plurality of discs having specially shaped outer peripheries which form recesses into which the bead areas of the tire are trapped and held during curing on the strip of retread rubber thereon. A cure press in U.K. Pat. No. 555,680 traps the tire bead area between a pair of outer mold sections mounted on an enlarged annular rim member. The bead areas are restrained from outward movement by the mold halves which are seated within the upturned flanges of the annular rim. French Pat. No. 1,301,779 shows another cure press having two half mold sections which move axially towards each other for trapping the tire including the bead areas therebetween.
Although the concept of trapping the bead area of a tire is shown in the prior art, no known cure press provides a construction which enables the use of segmented matrices, provides for the self centering of the tire, while providing tailored support to the entire casing and bead area of the tire and which uses a standard innertube for inflating the tire within the press as does my invention.